双阳离子型离子液体[C4(MIM)2][PF6]2的比热容测定及其模型化

利用差示扫描量热计(DSC)测定了双阳离子型离子液体1,1′-(丁烷-1,4-二基)-双(3-甲基-1H-咪唑鎓-1-基)双六氟磷酸盐([C4(MIM)2][PF6]2) 在293.15～513.15 K 温区内的摩尔比热容。结果表明，在 293.15～363.15 K 和 398.15～513.15 K 温区内，该化合物无相变及其他热异常现象发生，比热容随温度变化符合二次方程。在 363.15～398.15 K 温区内，该物质发生固-液熔化相变，其熔化温度、熔化焓及熔化熵分别为 384.71 K、28.243 kJ/mol 和 73.414 J/（K·mol）。根据热力学函数关系式，计算出 [C4(MIM)2][PF6]2 相对于标准参考温度298.15 K的热力学函数值。采用基团贡献法对液相区的热容进行了估算，结果表明，估算值与实验值符合很好。

Measurement and modeling of the molar heat capacity of the dicationic ionic liquid [C_4(MIM)_2][PF_6]_2

The molar heat capacity of the dicationic ionic liquid 1,1′-(butane-1,4-diyl)-bis(3-methyl-1H-imidazolium-1-yl) dihexafluorophosphate ([C₄(MIM)₂][PF₆]₂ ) has been measured using a differential scanning calorimeter (DSC) at temperatures from 293.15 K to 513.15 K. No phase transition or other thermal anomaly was observed in the temperature ranges 293.15-363.15 K and 398.15-513.15 K, in which the molar heat capacities were fitted to two polynomials. The melting point, molar enthalpy and entropy of fusion were determined to be 384.71 K, 28.243 kJ/mol and 73.414 J/(K·mol), respectively. The thermodynamic functions of [C₄(MIM)₂][PF₆]₂ relative to the reference temperature 298.15 K were derived based on the heat capacity data. A group contribution method was used to calculate the molar heat capacity of [C₄(MIM)₂][PF₆]₂ in the liquid region. The results showed that the calculated values are in good agreement with the experimental values.